Bohuslän & Gullmarsfjord

Diving here is mostly done from the road. Centres along the coast, Lysekil and Smögen among them, fill tanks and run boats, but plenty of divers simply park above a granite slab, kit up on the rock and walk in, because the shore falls away fast enough that there is no long surface swim to reach anything worth seeing. Boat days are kept for the outer skerries and the deeper wrecks, and they are decided by wind rather than by tide: the tidal range on this coast is a matter of centimetres, so it is the forecast that cancels a day.

The rock does the work. Bohuslän granite continues below the surface as slabs, fissures and clean vertical faces, with kelp in the shallows giving way to walls of soft coral, anemone and sponge. Sites split into two families. The inner fjords and sounds are sheltered, darker and siltier, layered enough that temperature and salinity can shift sharply on the way down. The exposed outer skerries — Väderöarna, off Fjällbacka, among them — sit in ocean water that clears earlier in the year and stays colder through the summer.

Gullmarn is the reason biologists have worked this coast since 1877, when the Kristineberg station opened on its shore. A sill of roughly 40 m pens a cold, salty layer into the basin behind it, so animals that normally sit far deeper turn up within reach of a shore entry, and wolffish are territorial enough to hold the same crevices for years. The Lophelia reef that helped earn Kosterhavet its status lies at around 80–90 m in the deep Koster channel, far past recreational depth; what divers actually work is the current-swept granite above it.

Which month you pick matters as much as which certification you hold. February and March are the photographer's window: short daylight, cold hands on the surface, fewer boats running, and water clear enough to read the whole shape of a wall. July to September is the sociable version, when Bohuslän is a Swedish holiday coast and beds, ramps and the popular entries all fill up. Either way, it rewards divers who like structure, macro and cold-water photography more than anyone counting big animals.